JP2004012878A - Method for processing end face of coated optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for processing an end face of a coated optical fiber, which method prevents the degradation in optical performance by bulging the coated optical fiber of a tapered section in just proportion. <P>SOLUTION: The method comprises cutting the coated optical fiber 20 to a prescribed length, inserting the cut fiber 20 into a through-hole 4 from a second aperture 3 so as to project the front end of the fiber 20 from a first aperture 2, heating a ferrule 1 to bulge the fiber 20, bringing a mirror finished surface 15 of a mirror finished surface plate 15 into pressurized contact with the ferrule 1, heating the end face of the fiber 20 to melt or soften and to bring the end face into contact with the surface 15, then cooling the end face of the fiber 20 to solidify the end face, and transferring the surface 15 to the end face of the fiber 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for processing an end face of an optical fiber core wire, in which a base is attached to a tip end and the end face of the optical fiber core wire is mirror finished.
[0002]
[Prior art]
A plastic optical fiber cable in which a base is fixed to a tip and an end surface of an optical fiber core wire is a mirror surface may be used as an optical fiber sensor head. Conventionally, to attach a base to the end of an optical fiber cable and make the end face of the optical fiber core mirror-finished, first remove the coating material of the optical fiber cable to expose the optical fiber core, and then insert the optical fiber core into the through hole of the base. And the optical fiber core wire and the base are firmly bonded with an adhesive. Next, the excess optical fiber core wire protruding from the tip end of the base is cut by a cutter or the like, and the cut surface is mechanically polished or a heated mirror surface plate is pressed against the end surface of the optical fiber core wire to make a mirror surface.
[0003]
Also, Japanese Patent Application Laid-Open No. 6-289237 discloses a method of mirror-finishing the end face of an optical fiber core wire of an optical fiber cable as described below. In this method, first, as shown in FIG. 6A, an optical fiber core wire 23 is inserted into a base 22 having a tapered portion 21 formed at the tip, and is projected from the base end port 24. Then, FIG. 6), the excess length of the optical fiber core wire 23 protruding from the base end port 24 is cut, and then, as shown in FIG. 6C, the heating body 25 is brought into contact with the outer peripheral surface of the base end of the base 22. The optical fiber core wire 23 located in the tapered portion 21 is enlarged, and at the same time, the mirror plate 26 is pressed against the base end port 24. In this manner, the end face of the optical fiber core wire 23 facing the tip end mouth 24 of the base is melted, and then the mirror plate 26 is cooled to solidify the end face of the optical fiber core wire 23, and the mirror surface 27 is changed to the end face of the optical fiber core wire 23. Transfer to According to such a method, the base can be easily attached to the tip of the optical fiber cable.
[0004]
[Problems to be solved by the invention]
However, in the above-described method, it is not easy to cut the optical fiber core wire projecting from the tip end of the base so that the excess length of the optical fiber core wire becomes constant, and the excess length becomes too long or too short. There was something to do. When the excess length of the optical fiber core wire is too long, as shown in FIG. 7A, the optical fiber core wire 23 may not fit in the base 22 when the optical fiber core wire 23 is enlarged by heating the die. . As a result, when the mirror plate is pressed against the base, the molten resin may enter the gap between the base and the mirror plate to form burrs. When removing the burrs, a part of the end face was sometimes peeled off. Further, when the excess length of the optical fiber core wire is too short, as shown in FIG. Not so, making the mirror finishing difficult. That is, in the above-described method, defects such as chipping of an end face may occur, and the optical performance of the optical fiber core wire may be reduced.
Further, in the above-mentioned method, the optical fiber core wire 23 is not sufficiently enlarged, and the optical fiber core wire may not be sufficiently filled in the tapered portion, particularly near the root portion (right side in FIG. 7) of the tapered portion. In some cases, the characteristics are deteriorated, or the base 22 and the optical fiber core wire 23 are not fixed with sufficient strength.
The present invention has been made based on the above background, and an object of the present invention is to firstly reduce the optical performance by enlarging the optical fiber core wire of the tapered portion without excess or shortage to prevent a decrease in optical performance. Secondly, by providing an end face processing method, it is possible to fill the optical fiber core wire of the tapered portion from the root of the tapered portion, and to firmly fix the base and the optical fiber core wire while preventing a decrease in optical characteristics. An object of the present invention is to provide a method for processing an end face of an optical fiber core wire.
[0005]
[Means for Solving the Problems]
In the method for processing an end face of an optical fiber core wire according to a first aspect of the present invention, a through-hole penetrating from the first opening to the second opening is formed, and the first opening is provided on the first opening side of the through-hole. An optical fiber that attaches a base having a tapered portion whose diameter is reduced as the distance from the base to the tip of the optical fiber core wire and mirror-ends the end face of the tip of the optical fiber core wire with a mirror plate having a heated mirror surface. A method of processing an end face of a core wire,
A cutting step of cutting the optical fiber core wire to a predetermined length,
An insertion step of inserting the optical fiber core wire cut in the cutting step from the second opening to a predetermined position through the first opening so that the tip of the optical fiber core wire projects from the first opening;
An enlarging process of heating the base and enlarging the optical fiber core wire;
A pressing step of pressing the mirror surface of the mirror plate to the base so as to cover the first opening;
Having a transfer step of heating and melting or softening the end face of the optical fiber core wire to make it contact the mirror surface, and then cooling and solidifying the end face of the optical fiber core wire to transfer the mirror surface to the end face of the optical fiber core wire. It is characterized by.
In the method for processing an end face of an optical fiber core wire according to a fourth aspect of the present invention, a through hole penetrating from the first opening to the second opening is formed, and the first opening is provided on the first opening side of the through hole. An optical fiber that attaches a base having a tapered portion whose diameter is reduced as the distance from the base to the tip of the optical fiber core wire and mirror-ends the end face of the tip of the optical fiber core wire with a mirror plate having a heated mirror surface. A method of processing an end face of a core wire,
An insertion step of inserting the optical fiber core wire from the second opening to the through hole to a predetermined position so that the tip of the optical fiber core wire projects from the first opening;
An enlarging process of heating the base and enlarging the optical fiber core wire;
A pressing step of pressing the mirror surface of the mirror plate to the base so as to cover the first opening while heating the base to enlarge the optical fiber core wire;
A heating step of heating the end face of the optical fiber core wire, melting or softening and bringing it into contact with the mirror surface, and then cooling and solidifying the end face of the optical fiber core wire, and transferring the mirror surface to the end face of the optical fiber core wire. The pressure contact step is performed after the enlargement step.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the method for processing an end face of an optical fiber core wire according to the present invention will be described. This end face processing method is a method in which a base is attached to the tip of an optical fiber cable in which a coating material is coated on the outside of an optical fiber core wire, and the end face of the optical fiber core wire is mirror-finished using a mirror plate.
FIG. 1 shows a base 1 used in the method for processing an end face of an optical fiber core wire according to this embodiment. The base 1 is formed with a through hole 4 penetrating from the first opening 2 to the second opening 3, and the first opening 2 is formed on the first opening 2 side of the through hole 4. A tapered portion 5 having a smaller diameter is formed as the distance from the second opening 3 increases, and a first insertion portion 6 is formed on the second opening 3 side. Further, a second insertion portion 7 having a smaller diameter than the first insertion portion 6 and connecting the tapered portion 5 and the first insertion portion 6 is formed. Here, the inner diameter of the first insertion portion 6 is substantially equal to the outer diameter of the optical fiber cable, and the inner diameter of the second insertion portion 7 is substantially equal to the outer diameter of the optical fiber core wire. . Since the through hole 4 is formed in this manner, insertion of the optical fiber cable is restricted, and only the optical fiber core wire is inserted into the second insertion portion 7 and the tapered portion 5.
[0007]
In the die 1, the taper angle θ of the tapered portion 5 is preferably 90 ° or less, more preferably 5 ° to 28 °. When the taper angle θ exceeds 90 °, an enormous amount of time is required and productivity may deteriorate. Here, the taper angle θ is an angle formed between two inner peripheral surfaces of the tapered portion 5 in a sectional view (FIG. 1) when the tapered portion 5 is cut along the central axis. .
In order to increase the heating efficiency when heating from the outside, it is preferable that the outer diameter of the cross section of the base 1 where the tapered portion 5 is formed is as small as possible.
[0008]
Next, a processing apparatus 10 used in the present embodiment is shown in FIG. The processing apparatus 10 includes a gripper 12 for gripping an optical fiber cable 11, a base heating body 13 for heating at least the outside of the tapered portion 5 of the base 1, and a cooling for at least the outside of the first insertion portion 6 of the base 1. A mirror cooling plate 14, a mirror plate 16 having a mirror surface 15, a mirror plate heater 17 for heating the mirror plate 16 in contact with the mirror plate 16, and a cooling means 18 for blowing and cooling the mirror plate 16. It is schematically configured.
In this processing apparatus 10, the holding means 12, the mirror plate 16, and the mirror plate heater 17 are movable in parallel to the axial direction of the optical fiber cable 11. Further, the mirror plate 16 can be brought into contact with the base 1, and the mirror plate heater 17 can be brought into contact with the mirror plate 16.
In addition, the clamp 19 for gripping the optical fiber cable 11 can be attached to the gripper 12. The mirror surface plate 16 has a mirror surface 15 at least at a portion in contact with the optical fiber core wire 20.
[0009]
Next, a method for processing the end face of the optical fiber core wire according to this embodiment will be described. In this end face processing method, first, as shown in FIG. 3A, in an exposing step, an end portion of a single-core optical fiber cable 31 having a cable outer diameter of 2.2 mm and an optical fiber core wire having an outer diameter of 1 mm. Is removed, and the optical fiber core wire 20 is exposed. Next, as shown in FIG. 3B, in the cutting step, the optical fiber cable 11 is fixed by the clamp 19, and the exposed optical fiber core wire 20 is cut into a predetermined length. Here, the predetermined length means that when the optical fiber core wire 20 is inserted through the base to a predetermined position, the volume of the portion protruding from the first opening is equal to the hollow portion of the tapered portion through which the optical fiber core wire is inserted. It is a length that is approximately equal to the volume.
At the time of cutting, a hot cutting machine 31 as a cutting means is used. The hot cut machine 31 cuts the optical fiber core wire 20 by a heated cutting blade. In this cutting step, since the optical fiber core wire 20 is cut in a state where the base is not attached to the optical fiber core wire, it is possible to cut the optical fiber core wire with high precision, and the optical fiber core wire can be cut using a heated cutting blade. 20 is cut, it is possible to cut with higher precision. In order to cut the optical fiber core wire 20 with high precision and smoothness, the cutting direction of the optical fiber core wire 20 (moving direction of the cutting edge of the cutting blade) and the side surface of the cutting edge of the cutting blade on the optical fiber core wire 20 side are required. The angle formed is preferably 5 ° to 30 °, more preferably 8 ° to 12 °. If the angle is too small, the side surface of the cutting blade may touch the end face of the optical fiber core wire 20, and if the angle is too large, the optical fiber core wire 20 may not be cut smoothly.
The temperature of the cutting blade is preferably from 180 to 270 ° C, more preferably from 220 to 240 ° C. If the temperature of the cutting blade is lower than 180 ° C., dents may occur on the cut surface, and if it exceeds 270 ° C., the surface of the cut surface may be rough. Further, the cutting speed (moving speed of the cutting blade) is preferably 5 to 15 mm / min. If the cutting speed exceeds 15 mm / min, dents may occur on the cut surface, and if it is less than 5 mm / min, the surface of the cut surface may be rough.
[0010]
Next, as shown in FIG. 3C, an adhesive 32 is applied to the outer peripheral surface of the optical fiber core wire 20 in an adhesive application step. Examples of the adhesive that can be used here include an epoxy resin.
Next, as shown in FIG. 3D, in the insertion step, the optical fiber core wire 20 is inserted through the second opening 3 through the through hole 4 so that the tip of the optical fiber core wire 20 protrudes from the first opening 2. To a predetermined position. Here, the predetermined position refers to an optical fiber in which the volume of the optical fiber core 20 protruding from the first opening 2 is substantially equal to the volume of the hollow portion of the tapered portion through which the optical fiber core is inserted. This is the position where the cable 11 is inserted. In this embodiment, if the optical fiber cable 11 is inserted until the shoulder 33 of the optical fiber cable 11 comes into contact with the wall surface 34 at the tip of the first insertion portion 6, the optical fiber cable 11 is inserted at a predetermined position. I have.
[0011]
Next, as shown in FIG. 4A, in the enlargement step, the clamp 19 is attached to the gripping means 12, and the base heating body 13 is brought into contact with the tip side peripheral surface of the base 1 and heated. At the same time, the cap cooling body 14 is brought into contact with the outer circumference of the cap 1 outside the first insertion portion 6 to cool the portion other than the end of the optical fiber cable 11 so as not to be enormous. In this manner, by heating the base 1, the optical fiber core wire 20 is heated, and the tip of the optical fiber core wire 20 located at the tapered portion 5 is gradually enlarged, thereby filling the tapered portion 5. At this time, the temperature of the base heating body 13 may be a temperature at which the optical fiber core wire 20 becomes enormous, and the temperature of the base cooling body 14 may be a temperature at which the optical fiber cable 11 does not become enormous.
Next, as shown in FIG. 4B, in the pressing step, the mirror plate 16 is attached to the base 1 so that the first opening 2 is closed by the mirror surface 15 while the base heating body 13 continues to heat the base 1. Press. In this pressure contact, the mirror plate 16 presses the optical fiber core wire 20 protruding from the first opening 2, so that the tapered portion 5 is filled.
[0012]
Next, as shown in FIG. 5A, in the transfer step, the mirror plate heating body 17 is brought into contact with the mirror plate 16, and the mirror plate plate 16 is pressed by the mirror plate heating body 17 to heat the mirror plate 16. Apply pressure. Then, the optical fiber core wire 20 is enlarged and the tapered portion 5 is filled without gaps, and the molten optical fiber core wire 20 is brought into contact with the mirror surface 15 of the mirror plate 16.
Then, as shown in FIG. 5B, while the mirror plate 16 is kept in contact with the base 1, the tip of the base 1 and the mirror plate 16 are cooled by using an air blowing nozzle as the cooling means 18, and the optical fiber is cooled. The end face of the core wire 20 is solidified, and the mirror surface 15 is transferred to the end face of the optical fiber core wire 20.
Finally, the base heating body 13, the base cooling body 14, and the mirror surface plate 16 (including the mirror surface heating body 17) are separated from the base 1, the optical fiber cable 11 is removed from the gripping means 12, and the optical fiber core wire is removed. The optical fiber cable 11 whose end face is processed is obtained.
[0013]
In the method for processing the end face of the optical fiber core wire according to the above-described embodiment, the optical fiber core wire 20 is cut into a predetermined length with high accuracy, and then the optical fiber core wire 20 is inserted into the through hole 4 of the base 1 to a predetermined position. Therefore, when the base 1 is heated by the base heating body 13 and the optical fiber core wire 20 is enlarged, the tapered portion 5 can be filled without excess or shortage. As a result, it is possible to eliminate the defect due to the difference in the excess length, and to cool the tip of the base 1 and the mirror plate 16 by the air blowing nozzle as the cooling means 18 to solidify the end face of the optical fiber core wire 20 and to reduce the light. Even if the mirror surface 15 is transferred to the end face of the fiber core wire 20, occurrence of defects such as chipping of the end face is prevented. Therefore, the optical performance of the optical fiber core wire 20 is excellent. Further, since the occurrence rate of defective products can be reduced, the yield can be improved.
[0014]
In the embodiment described above, the adhesive 32 is applied to the outer peripheral surface of the optical fiber core wire 20 before the optical fiber core wire 20 is inserted into the through hole 4, so that the base 1 and the optical fiber core wire 20 are adhered to each other. Thus, the optical fiber core wire 20 can be fixed at a predetermined position. As a result, the tapered portion 5 can be filled more or less, so that the end face of the optical fiber core wire 20 can be made more uniform and the optical performance can be further improved.
Further, in the above-described embodiment, since the tip of the optical fiber core wire 20 is gradually enlarged in the enlargement step before the pressure welding step, the optical fiber core wire 20 is gradually filled from the root portion of the tapered portion 5. can do. In the subsequent pressing step, the mirror plate 16 is pressed against the base 1 while the heating of the optical fiber core wire 20 preheated in the enlarging step by the base heating body 13 is continued. The core wire 20 can be filled. Therefore, the base 1 and the optical fiber core wire 20 are firmly fixed, and the deterioration of the optical characteristics due to the end face treatment does not occur.
[0015]
Note that the present invention is not limited to the end face processing method of the embodiment described above. For example, the optical fiber core wire may be heated and pressurized by integrating the mirror body and the end face heating body. In this way, when the mirror body and the end surface heating body are integrated, the processing apparatus is simplified. In the adhesive application step, the adhesive may be applied to the inner surface of the through hole 4 instead of applying the adhesive 32 to the outer peripheral surface of the optical fiber core wire 20. Further, it may be applied to both the outer peripheral surface of the optical fiber core wire 20 and the inner surface of the through hole 4.
[0016]
Further, in the end face processing method of the embodiment described above, the enlarging step, the pressing step, and the transferring step are performed in order, but the present invention is not limited to this. For example, the enlarging step and the pressing step may be performed simultaneously, or the pressing step and the transferring step may be performed simultaneously. Further, the enlargement step, the pressing step, and the transfer step may be performed simultaneously.
Furthermore, it is not necessary to have an exposure step, a cutting step, and an adhesive application step.
Although a single-core optical fiber cable is processed, a multi-core optical fiber cable may be processed. As the optical fiber cable to be processed, a cable in which an organic or inorganic optical fiber core wire is covered with a sheath such as polyethylene is used.
[0017]
【The invention's effect】
In the present invention, the optical fiber core wire is cut into a predetermined length with high precision, and then the optical fiber core wire is inserted into the through hole of the base until it reaches a predetermined position. Then, the tapered portion can be easily filled without excess or shortage. As a result, it is possible to eliminate defects due to differences in excess length, cool the tip of the base and the mirror surface plate, solidify the end surface of the optical fiber core wire, and transfer the mirror surface to the end surface of the optical fiber core wire. In addition, the occurrence of defects such as chipping of the end face can be prevented. Therefore, the optical performance of the optical fiber core wire is excellent. Further, according to the end face processing method of the present invention, after the enlarging step, the optical fiber core wire is tapered to perform the pressure contacting step of pressing the mirror surface plate to the die while continuing to enlarge the optical fiber core wire by heating the die. It can be filled up to the root of the portion, and the optical fiber core wire and the base can be firmly fixed without deteriorating the optical characteristics. Furthermore, the yield of defective products can be reduced, so that the yield can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a base used in an embodiment of a method for processing an end face of an optical fiber core wire of the present invention.
FIG. 2 is a cross-sectional view showing a processing apparatus used in an embodiment of the method for processing an end face of an optical fiber core wire according to the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of the method for processing an end face of an optical fiber core wire according to the present invention.
FIG. 4 is a cross-sectional view showing an embodiment of the method for processing an end face of an optical fiber core wire according to the present invention.
FIG. 5 is a cross-sectional view showing an embodiment of the method for processing an end face of an optical fiber core wire according to the present invention.
FIG. 6 is a sectional view showing an example of a conventional method for processing an end face of an optical fiber core wire in the order of steps.
FIGS. 7A and 7B are cross-sectional views when the optical fiber core wire protruding from the base is cut and enlarged, where FIG. 7A is a diagram when the extra length is too long, and FIG. 7B is a diagram when the extra length is short. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base 2 First opening 3 Second opening 4 Through hole 5 Tapered part 6 First insertion part 7 Second insertion part 11 Optical fiber cable 15 Mirror surface 16 Mirror surface plate 20 Optical fiber core wire

Claims (9)

A through-hole penetrating from the first opening to the second opening is formed, and a tapered portion having a diameter reduced as the distance from the first opening is formed on the first opening side of the through-hole. Attached to the tip of the optical fiber core wire, the end face of the tip of the optical fiber core wire, the end face processing method of the optical fiber core wire mirror-finished by a mirror plate having a heated mirror surface,
A cutting step of cutting the optical fiber core wire to a predetermined length,
An insertion step of inserting the optical fiber core wire cut in the cutting step from the second opening to a predetermined position through the first opening so that the tip of the optical fiber core wire projects from the first opening;
An enlarging process of heating the base and enlarging the optical fiber core wire;
A pressing step of pressing the mirror surface of the mirror plate to the base so as to cover the first opening;
Having a transfer step of heating and melting or softening the end face of the optical fiber core wire to make it contact the mirror surface, and then cooling and solidifying the end face of the optical fiber core wire to transfer the mirror surface to the end face of the optical fiber core wire. A method for processing an end face of an optical fiber core wire, the method comprising: The optical fiber core according to claim 1, further comprising an adhesive application step of applying an adhesive to an inner surface of the through hole and / or an outer peripheral surface of the optical fiber core between the cutting step and the insertion step. End face processing method. The end face of the optical fiber core wire according to claim 1 or 2, wherein the pressing process is performed after the enlarging process, and the pressing process is performed while heating the die to enlarge the optical fiber core wire. Processing method. A through-hole penetrating from the first opening to the second opening is formed, and a tapered portion having a diameter reduced as the distance from the first opening is formed on the first opening side of the through-hole. Attached to the tip of the optical fiber core wire, the end face of the tip of the optical fiber core wire, the end face processing method of the optical fiber core wire mirror-finished by a mirror plate having a heated mirror surface,
An insertion step of inserting the optical fiber core wire from the second opening to the through hole to a predetermined position so that the tip of the optical fiber core wire projects from the first opening;
An enlarging process of heating the base and enlarging the optical fiber core wire;
A pressing step of pressing the mirror surface of the mirror plate to the base so as to cover the first opening while heating the base to enlarge the optical fiber core wire;
A heating step of heating the end face of the optical fiber core wire, melting or softening and bringing it into contact with the mirror surface, and then cooling and solidifying the end face of the optical fiber core wire, and transferring the mirror surface to the end face of the optical fiber core wire. Wherein the pressure contacting step is performed after the enlarging step. A first insertion portion is formed on the second opening side of the through hole, and a second insertion portion having a smaller diameter than the first insertion portion is provided between the first insertion portion and the tapered portion. The method for processing an end face of an optical fiber core wire according to any one of claims 1 to 4, wherein is formed. The method for processing an end face of an optical fiber core wire according to any one of claims 1 to 5, wherein the mirror body is integrated with a heating means. The method for processing an end face of an optical fiber core wire according to any one of claims 1 to 6, wherein a taper angle of the tapered portion is 90 ° or less. The method for processing an end face of an optical fiber core wire according to claim 7, wherein a taper angle of the tapered portion is 5 ° to 28 °. 9. An optical fiber cable in which a coating material is coated on the outer side of an optical fiber core wire, and an exposing step of exposing the optical fiber core wire by removing the coating material at the end of the optical fiber cable. 3. The method for processing an end face of an optical fiber core wire according to item 1.

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